Which OSI model layer is responsible for reliable delivery of data between devices?

The Transport Layer ensures reliable data delivery between devices by managing segmentation, acknowledgment, and error recovery. Protocols like TCP (Transmission Control Protocol) operate at this layer, ensuring end-to-end communication. For example, TCP uses mechanisms like acknowledgments, retransmissions, and flow control to guarantee that data is delivered without loss, duplication, or errors. This layer also handles multiplexing, allowing multiple applications to use the network simultaneously by assigning unique ports. In essence, the transport layer acts as a bridge between the higher application layers and the lower network infrastructure, maintaining data integrity and ensuring a seamless user experience. Why Other Options Are Incorrect :

1. Physical Layer : Handles the transmission of raw bits over the physical medium, without ensuring reliability.
2. Data Link Layer : Ensures error-free transmission over a single link but does not provide end-to-end reliability.
3. Network Layer : Handles routing and addressing but does not guarantee reliable data delivery.
4. Application Layer : Focuses on user interaction and does not handle data transmission reliability.